US 20070088410 A1
A phototherapy system having a rigid support surface adapted to support a patient without substantial deformation; a light source disposed so as to transmit light through the support surface; and a mask adapted to permit light transmission from the light source through a first portion of the support surface and to limit light transmission from the light source through a second portion of the support surface.
1. A phototherapy system, comprising:
a rigid support surface adapted to support a patient without substantial deformation;
a light source disposed so as to transmit light through the support surface; and
a mask adapted to permit light transmission from the light source through a first portion of the support surface and to limit light transmission from the light source through a second portion of the support surface.
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This application claims the benefit of U.S. Provisional Application No. 60/689,339, filed Jun. 11, 2005, which is incorporated herein by reference in its entirety.
This invention relates to devices for the phototherapeutic treatment of illness and diseases.
Phototherapy is a promising clinical tool for the treatment for many conditions, including seasonal affective disorder, bulimia nervosa, herpes, psoriasis, sleep disorders, acne, and skin cancer.
Phototherapy is especially promising as a treatment for hyperbilirubinemia, a common condition affecting about 60% of all newborns. Hyperbilirubinemia is caused by the accumulation of excess bilirubin in the blood of the infant. This excess bilirubin turns the skin and sclera a characteristic yellow color. If left untreated, extreme cases of hyperbilirubinemia can result in neurological insult (kemicterus) or even death. A common treatment for hyperbilirubinemia is phototherapy, in which the infant is exposed to light in a range corresponding to the absorption spectra for bilirubin (blue-green, 400-550 nm). This light energy changes the form of the bilirubin to a different isomer that is more readily eliminated by the body.
Phototherapeutic light can be provided from above (by using an overhanging panel), from below (by using an illuminated pad or bed), from all sides (by using a phototherapeutic garment or blanket), or combinations thereof. Prior phototherapy systems are described, e.g., in Kremenchugsky U.S. Pat. No. 5,339,223; Rosen U.S. Pat. No. 6,045,575; Russell U.S. Pat. No. 6,290,713; Larsson U.S. Pat. No. 5,792,214; Nicholas U.S. Pat. No. 5,400,425; Vreman U.S. Pat. No. 6,596,016; Williams U.S. Pat. No. 6,872,220; Williams U.S. Pub. No. 2004/0039428; Bansal U.S. Pub. No. 2004/0068305; and Gardner U.S. Pub. No. 2006/0100675.
Regardless of the technique used, it is important to limit the “leakage” of phototherapeutic light; that is, phototherapeutic light not absorbed by the patient. Ideally, all the emitted light is absorbed by the patient, however a significant percentage of the phototherapeutic light never strikes the patient. This is especially true using overhanging panels and illuminated pads or beds. This leakage, or extraneous light, is simply wasted, and some individuals report nausea or discomfort from prolonged exposure to leaked phototherapeutic light. Systems and devices are therefore needed to reduce the amount of leaked or extraneous light during phototherapy.
In addition, phototherapy systems, particularly for infants, should be safe, effective and easy to use. For example, any extraneous heat generated a phototherapy system should be safely handled. Providing a comfortable and hygienic environment for the patient is also important.
The present invention is a device that provides phototherapeutic light from below a patient. The device includes a phototherapeutic light or lights, and a structure or structures for holding the light(s) and for supporting the subject (typically an infant). The device also includes means for reducing or minimizing the dispersion of extraneous light.
One aspect of the invention provides a phototherapy system having a rigid support surface adapted to support a patient without substantial deformation, a light source (such as, e.g., a plurality of light-emitting diodes (LEDs)) disposed so as to transmit light through the support surface, and a mask adapted to permit light transmission from the light source through a first portion of the support surface and to limit light transmission from the light source through a second portion of the support surface. The light source may comprise a plurality of light sources operating at a plurality of colors. The mask may be further adapted to block or attenuate light transmission from the source through the second portion. The mask may include a thermochromic material, a patient location sensor, and/or a fluid-filled pad.
In some embodiments, the invention includes a patient orientation element, e.g., a visible shape in or on the support surface. In such embodiments, the light source (e.g., LEDs) may have a substantially non-uniform concentration with respect to the orientation element. For example, the patient orientation element may have a head area adapted to orient the head of the patient with respect to the support surface. The light source may comprise a plurality of LEDs having a concentration greater near the head area than in another area of the orientation element.
In some embodiments, the phototherapy system also includes a cooling assembly adapted to control heat within the system. The cooling system may include, e.g., a fan and/or a temperature sensor.
In some embodiments, the phototherapy system has a light level controller, such as a temperature sensor.
Some embodiments of the invention have a mattress adapted to be disposed between the patient and support surface and to transmit light from the support surface to the patient. The system may also include a mattress cover disposed over at least a portion of the mattress and adapted to transmit light.
In some embodiments, the phototherapy system also includes a pressure-sensitive switch adapted to control the light source.
All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.
The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:
One aspect of the invention is a phototherapy system which includes a rigid support surface adapted to support a patient without substantial deformation, a light source disposed so as to transmit light through the support surface, and a mask adapted to permit light transmission from the light source through a first portion of the support surface and to limit light transmission from the light source through a second portion of the support surface. The system preferably reduces or minimizes the amount of leakage of phototherapeutic light from the system so that the light is primarily absorbed by the patient while reducing light exposure to others. In some embodiments the system can minimize or reduce leakage by responding to the patient's position or orientation on the system, while in other embodiments the minimization or reduction is independent of the position of the patient. The system may be used in the treatment of hyperbilirubinemia or other conditions treatable using phototherapy.
In preferred embodiments the rigid support structure includes a base. Generally, the base provides support for additional components of the system, as well as for a patient receiving phototherapy. Base may be of any suitable size and shape, however, it will be of sufficient size to support at least an infant. The base and/or base cover, as described below, may have walls 16 as shown in
The base may also comprise additional system components including, without limitation, a power supply, a cooling assembly including fans, vents 14 as shown in
The rigid support surface may also include a base cover which is adapted to be coupled to the base. The base cover may be coupled with the base by any known method, including screws, snap together pieces, or any other suitable fastening mechanism known in the art. In some embodiments the base cover can act to protect the system components housed within the base, such as the light source or the power supply. The base cover may, additionally, comprise system components such as, without limitation, a power switch 15, manual power level controller as described below, or any of the other system components that may be housed in the base described herein. The base cover may be optional, for example, when a pressure activated light source is used as described below.
The system of the present invention includes a light source which provides the phototherapy to a patient. In some embodiments the light source comprises a plurality of LEDs. In preferred embodiments the light source comprises a plurality of LEDs that emit light in the range of about 400 to about 550 nm. In more preferred embodiments the LEDs emit blue light in the range of about 450 to about 470 nm, which matches the peak absorption at which bilirubin absorbs light, and is thus considered to be the most effective treatment for hyperbilirubinemia. Any suitable number or position of LEDs may be used.
Alternatively, other types of LEDs, lasers, or laser diodes also may be used. The light source may be multicolored LEDs, or the light source may comprise a plurality of light sources operating at a plurality of colors, such as in the Natus neoBLUE LED Phototherapy System®. The light source may comprise blue and yellow LEDs. In such embodiments, generally, the blue LEDs provide the treatment light, and the yellow LEDs provide color balance, making it easier on a caregiver's eyes. For the treatment of neonatal hyperbilirubinemia, the preferred treatment color of LEDs is blue, although green LEDs also may be effective. The treatment of other conditions may require differently colored LEDs. For example, herpes may be most effectively treated by red LEDs, seasonal affective disorder may be treated by white or yellow LEDs, and psoriasis may be treated by ultraviolet LEDs. Other light sources can be used, including fluorescent lights. The condition being treated and the light source used for the treatment may vary while carrying out a purpose of the invention to prevent or minimize exposure of phototherapeutic light to those other than the patient.
The intensity or power level of the lights throughout the light source may also vary depending on the likelihood that the patient's body will be exposed to an area of the system. Depending on the size of the patient, for example, the intensity of the lights throughout the light source can be adjusted to prevent “leakage” of phototherapeutic light, that is, light that is emitted and not absorbed by the patient. For example, if an infant of smaller than average size requires phototherapy, the intensity of lights towards the periphery can be decreased while maintaining the normal intensity of the lights near the center, as a small infant may require less light than a baby of, for example, textbook normal size. The intensity may be adjusted manually by a light level controller housed preferably within the base or base cover, or the system may have a temperature sensor which detects, for example, overheating, and can automatically adjust the intensity accordingly. The system may comprise a device capable of making the plurality of lights separately addressable so that they may be selectively illuminated in a particular pattern to achieve a particular therapeutic result. The system may have a non-uniform concentration of lights throughout the light supporting structure, the power of which may be simultaneously varied throughout the light source to achieve the desired light emission pattern. However, the system may also have a uniform concentration of lights throughout the light structure without departing from the intent of the invention.
The system includes any suitable interconnection technology to provide an electrical circuit among the power supply, the light source, power switch, cooling assembly, light level controller, and any other electrical component of the system described herein. For example, the system may also include a timer which can automatically shut off the light source after a desired exposure time. Electrical components are preferably housed within the base or base cover, but may additionally be housed within other system components as well.
This aspect of the system also comprises a mask adapted to permit light transmission from the light source through a first portion of the rigid support surface and to limit light transmission from the light source through a second portion of the support surface. The mask helps reduce the amount of emitted light exposed to individuals other than the patient.
The interface between transparent region 24 and a mask 22 forms a transition zone 23 that may have substantially the same shape and position as the outline of the most peripheral lights in the light source 32. The transparent region 24 is positioned approximately above the light source 32, while the mask 22 is positioned approximately above the light supporting structure 30 where there is no light source. The light source may, however, be uniformly distributed throughout the light supporting structure, in which case the transition zone 23 would not have substantially the same shape and position of the outline of the most peripheral lights in the light source.
In some embodiments the mask substantially blocks light, particularly light emitted from the light source, from traveling through it rather than merely attenuating or diffusing the light. The transparent region permits light to transmit through the support surface in areas where a patient in likely to be positioned, while the mask helps limit the amount of emitted light that is exposed to others which is not absorbed by the patient. The mask may be any suitable material that substantially blocks light from traveling through it, such as without limitation, an opaque plastic material. In such an embodiment, a blanket or other cover also could be placed over the patient, thereby further blocking the transmission of extraneous phototherapeutic light into the environment. However, such a blanket might preclude simultaneous treatment with phototherapeutic light from above the patient.
In some embodiments the mask diffuses or attenuates light from the light source rather than blocks it completely. Attenuating includes, e.g., filtering certain colors, diffusing the light, or any other alteration of the light passing through the mask. Because a patient is more likely to be positioned in the center of the rigid support surface, he or she will be exposed primarily to undiffused phototherapeutic light, while onlookers will primarily be exposed to the diffused or attenuated light from the periphery. This will reduce the amount of exposure to non-patient persons such as caregivers.
In some embodiments the mask comprises a thermochromic material, such as ink or paint. Thermochromic material involves the use, e.g., of liquid crystal or leuco dye technology. After absorbing a certain amount of light or heat, the crystal or molecular structure of the pigment reversibly changes in such a way that it absorbs and emits light at different wavelengths than at lower temperatures. Once the thermochromic material absorbs heat it can become transparent. As used herein, thermochromic material can be used as a mask in the system, and once it absorbs heat from a patient's body through conduction, it can become transparent and allow light to pass through the transparent region. It should remain opaque at room temperature, but become transparent as it approaches body temperature.
The system may comprise a cooling assembly as described below to ensure that heat from the light source does not cause the thermochromic material to change color. In some embodiments a cooling assembly fan may be placed between the light source 32 and the mattress 40 or may be placed beneath the light source 32 in the base 10, providing airflow between the light source 32 and mattress 40.
The amount of opaque liquid or gel 46 that is inside the transparent mattress 40 is preferably great enough such that when the weight of the body displaces the liquid or gel, there are not any transparent pockets or bubbles that are not directly beneath the patient. In addition, however, the amount of liquid or gel in the transparent pouch is preferably not great enough such that the body weight can not displace enough of the liquid or gel to provide any transparent regions beneath the patient. This would prevent any light from the light source from being transmitted to the patient. Preferably when the patient is on the mattress 40, the liquid or gel in the pouch is displaced and exerts enough force on the outer edges of the mattress so that there are not any transparent regions that are not directly beneath the patient, while the area of the mattress directly below the patient is substantially transparent. Thus, the size of the transparent pouch and the volume of liquid or gel must be chosen to carry out the intent of the invention.
Another embodiment would include placing a substance such as paraffin in the pad that changes phase and color from, for example, opaque to transparent when warmed by the baby's body. Thus, the area underneath the infant would be clear, while other areas would remain opaque, similar to the thermochromic paint embodiment described above.
Another embodiment would include the use of a filter material, e.g., a pressure sensitive or pressure indicating film, which changes color and/or opacity when compressed by the baby's weight. Pressurex®, made by SPI, e,g., could by used as such a pressure sensitive or pressure indicating film to indicate the location of the patient.
In another embodiment of the system shown in
In some embodiments the system comprises one or more patient location sensors. The sensor senses the location of the patient on the rigid support surface, communicates the location of the patient to a light level controller within the system, and the light level controller either directly or indirectly illuminates only those lights that correspond to locations substantially directly beneath where the patient is situated on the rigid support surface.
In some embodiments as shown in
The rigid support surface may comprise a mattress 40 which can be placed above the base cover to provide comfortable cushioning underneath the patient. The mattress 40 may have filler material 42 as shown in
The mattress 40 may also be concave to help ensure that the patient remains in place during the phototherapy session. The amount of filler material 42 may be adjusted within the mattress to help produce the concave region. For example, less filler material may be used near the center of the mattress to create a concave shape to the mattress. In addition, by placing less filler material near the center of the mattress, not only is a concave region created, but the region is also more transparent to light as there is less filler material, which enhances the amount of light that may be absorbed by the patient.
The mattress may serve a secondary purpose of diffusing the phototherapeutic light before it is absorbed by the patient, providing a more even exposure of light to the patient's skin than without a diffusive layer. The mattress can be made of polyester or polyurethane and/or other suitable materials. A weave or fabric can be placed on top of the mattress for the patient's comfort. A mattress cover may be fitted on top of the mattress, and this cover may be disposable. The cover may have light diffusion properties similar to the mattress.
The system is configured such that a blanket may be placed over a patient for warmth during phototherapy, or a blanket may be incorporated into the system. The system can also be used in conjunction with an overhead phototherapy system for additional exposure, for example, as is described in pending U.S. patent application Ser. No. 10/265,970 (Publication No. 2004/0068305) or Ser. No. 10/651,906 (Publication No. 2005/0149149), both of which are incorporated herein by reference in their entirety.
In some embodiments the phototherapy system of the present invention comprises a patient orientation element. The orientation element assists a caregiver in placing a patient in the right position and/or orientation on the rigid support surface. As shown in
In preferred embodiments the phototherapy system comprises a light level controller. The light level controller may be housed within the base or base cover, and controls the power level or intensity of the light source, either controlling individual lights or the light source as a whole. The light level controller may be connected to a manual controller on the outside of the device, similar in position to the power switch 15, so that a caregiver can control the level of the lights, or the light level controller may be housed within the system and operates automatically based on temperatures sensors which sense the temperature of the system. In the later case, the light level controller comprises at least one temperature sensor that senses when the base cover becomes too warm for the patient's safety due to the light source emissions. Any reasonably suitable temperature sensor known to those skilled in the art may be used, for example, a thermocouple. When the sensor directly or indirectly senses the surface temperature of the base cover is greater than, for example, a threshold level programmed into a memory of the light level controller, the light source, either in its entirety or individual lights, will automatically shut off to prevent safety hazards to the patient. A fan, as will be described below as part of a cooling assembly, can also draw cool ambient air into and through the system and over the LEDs to cool them off by convection, and then vents can vent the warmed air out the vents of the system.
In preferred embodiments the system comprises a cooling assembly adapted to facilitate the removal of heat from the system. LEDs generate heat within the system, and as the system is enclosed around the LEDs, the heat has no way to efficiently exit the system and the patient may be in danger of exposure to such increases in heat. Therefore a thermal management system is required to ensure the safety of the patient. Natural convection thermal management techniques are well known in the art, and the system preferably comprises at least one fan to draw cooler ambient air into the system through vents 19 in the base, and draw the cool air over warmer system components such as the LEDs, where by convention the heat is transferred from the warmer components to the cooler air, and the warmed air is then vented out of the system through vents 14 as shown in
While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.